A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds , members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic material such as twigs, grass, and leaves, or may be a simple depression in the ground, or a hole in a rock, tree, or building. Human-made materials, such as string, plastic, cloth, or paper, may also be used. Nests can be found in all types of habitat .
71-574: Nest building is driven by a biological urge known as the nesting instinct in birds and mammals. Generally each species has a distinctive style of nest. Nest complexity is roughly correlated with the level of parental care by adults. Nest building is considered a key adaptive advantage among birds, and they exhibit the most variation in their nests ranging from simple holes in the ground to elaborate communal nests hosting hundreds of individuals. Nests of prairie dogs and several social insects can host millions of individuals. Nest building (nidification)
142-434: A caste structure similar to the social insects while building extensive burrows that house hundreds of individuals. Versatility in use of construction material may be an adaptive advantage (less energy used to gather materials) or a disadvantage (less ability to specialize construction). The available evidence suggests that natural selection more often favors specialization over flexibility in nest construction. At
213-526: A "mima prairie" landscape marked by huge areas of flat land punctuated by mounds 30 metres (98 ft) wide and 2 metres (6.6 ft) high. Similar structures exist in the United States , created by pocket gophers , and Argentina , rodents of the genus Ctenomys . Nests constructed by megapode birds have been mistaken for anthropological features by professionals, due to their exceptional height (10 metres [33 ft]) and abundance (hundreds in
284-487: A gelatinous mass which they attach to underwater vegetation to prevent eggs from washing away. Nests can have other protective qualities. For example, the female Fletcher frog beats secreted mucus into a froth, creating a structure that serves as a line of defense against thermal extremes, predation, and desiccation. Fish engage in nest building activities ranging from simply scooping out sediment to building enclosed structures out of plant matter. Male sticklebacks produce
355-542: A green or blue ground colour, while protoporphyrin IX produces reds and browns as a ground colour or as spotting. Non-passerines typically have white eggs, except in some ground-nesting groups such as the Charadriiformes , sandgrouse and nightjars , where camouflage is necessary, and some parasitic cuckoos which have to match the passerine host's egg. Most passerines, in contrast, lay coloured eggs, even if there
426-436: A longer fetal development. Comparatively anatomically simple animals will be able to go through the full development and leave the egg in a form reminiscent of the adult animal. This is the situation found in hagfish and some snails . Animals with smaller size eggs or more advanced anatomy will still have a distinct larval stage, though the larva will be basically similar to the adult animal, as in lampreys , coelacanth and
497-403: A naked egg cell. Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The yolk is concentrated in one part of the egg (the vegetal pole ), with the cell nucleus and most of the cytoplasm in the other (the animal pole ). The cell cleavage is uneven, and mainly concentrated in the cytoplasma-rich animal pole. The larger yolk content of the mesolecithal eggs allows for
568-414: A protective shell , either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark and
639-523: A shell and would dry out in the air. Even air-breathing amphibians lay their eggs in water, or in protective foam as with the Coast foam-nest treefrog, Chiromantis xerampelina . Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one (as in condors ) to about 17 (the grey partridge ). Some birds lay eggs even when not fertilized (e.g. hens ); it
710-414: A single location). Nest architecture may be as useful for distinguishing species as the animals' physical appearance. Species identified through such means are called ethospecies . This is especially common in wasps and termites, but also can apply to birds. In most animals, there is some variation in nest construction between individuals. Whether these differences are driven by genetics or learned behavior
781-427: A special enzyme in their kidneys that they use to bind plants together. The American alligator is known for its parenting skills. They build large nests of mud and vegetation on river banks or vegetation mats. The female digs a hole in the center to lay her eggs, covers them, and then guards them for two months until they hatch. When eggs start to hatch, she breaks open the nest which has hardened over time and leads
SECTION 10
#1732779827973852-494: A usable structure. The tailorbirds stitch together leaves to provide cover for their nest sites. The sociable weaver builds large communal nests in which many individual nests reside. They divide the nest using walls of grass placed atop a base of large sticks. At the entrances to the nest, sharp sticks are placed to ward off intruders. A single communal site can measure 2 metres (6.6 ft) in height and 8 metres (26 ft) in width. As many as 300 mating pairs may reside in
923-495: Is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote ) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches. Most arthropods , vertebrates (excluding live-bearing mammals ), and mollusks lay eggs, although some, such as scorpions , do not. Reptile eggs, bird eggs , and monotreme eggs are laid out of water and are surrounded by
994-415: Is common among birds. In general, nest complexity increases in relation to the level of parental care provided. Nest building reinforces social behavior, allowing for larger populations in small spaces to the point of increasing the carrying capacity of an environment. Insects that exhibit the most complex nidification also exhibit the greatest social structure. Among mammals, the naked mole-rat displays
1065-589: Is common within the nest. Ant nests alone support symbiotes spanning six classes of arthropods which includes 35 families just from the beetles . Nesting instinct Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.237 via cp1104 cp1104, Varnish XID 206397925 Upstream caches: cp1104 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 07:43:48 GMT Egg (biology) An egg
1136-414: Is known as oviparity , in which the female lays undeveloped eggs that are externally fertilized by a male. Typically large numbers of eggs are laid at one time (an adult female cod can produce 4–6 million eggs in one spawning) and the eggs are then left to develop without parental care. When the larvae hatch from the egg, they often carry the remains of the yolk in a yolk sac which continues to nourish
1207-425: Is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs. Many animals feed on eggs. For example, principal predators of the black oystercatcher 's eggs include raccoons , skunks , mink , river and sea otters , gulls , crows and foxes . The stoat ( Mustela erminea ) and long-tailed weasel ( M. frenata ) steal ducks' eggs. Snakes of
1278-416: Is no need of cryptic colors. However, some have suggested that the protoporphyrin markings on passerine eggs actually act to reduce brittleness by acting as a solid-state lubricant. If there is insufficient calcium available in the local soil, the egg shell may be thin, especially in a circle around the broad end. Protoporphyrin speckling compensates for this, and increases inversely to the amount of calcium in
1349-446: Is not uncommon for pet owners to find their lone bird nesting on a clutch of unfertilized eggs, which are sometimes called wind-eggs. The default colour of vertebrate eggs is the white of the calcium carbonate from which the shells are made, but some birds, mainly passerines , produce coloured eggs. The colour comes from pigments deposited on top of the calcium carbonate base; biliverdin and its zinc chelate , and bilirubin , give
1420-635: Is often driven by a biological urge in pregnant animals to protect one's offspring known as the nesting instinct . Animals build nests to protect their eggs , their offspring, or themselves from danger. The simplest nest structures are adapted to hide eggs from predators , shield them from the sun or other environmental factors, or simply keep them from being scattered in ocean currents . In some cases, nests also help provide safety in numbers for egg-laying animals. Many nest builders provide parental care to their young, while others simply lay their eggs and leave. Brooding (incubating eggs by sitting on them)
1491-461: Is the most common construction material for nests. Other common materials include fur or feathers , perhaps from the animal itself, mud or dirt , fecal matter , and specialized secretions from the animal's body. Nest building can have a substantial impact on the environment in which animals live. The combined digging activity of termites and mole-rats in South Africa has created
SECTION 20
#17327798279731562-408: Is thought to act as a shock absorber, protecting the calcite shell from fracture during incubation, such as colliding with other eggs in the nest. Most bird eggs have an oval shape , with one end rounded and the other more pointed. This shape results from the egg being forced through the oviduct . Muscles contract the oviduct behind the egg, pushing it forward. The egg's wall is still shapeable, and
1633-512: Is unique in that individuals of that species build their nests in wood, bamboo culms, agave stalks, and other similar materials, although their preferred nesting material is pine or cedar lumber. When digging the nests, they use the wood shavings scraped from the wall to create partitions within the tunnels. The nests are usually round and have about 1-4 tunnels, each with multiple branches. Because these materials are often useful for humans in construction, X. virgininica's nesting behavior presents
1704-497: Is unknown. With the exception of a few tunneling mammals, nest builders exhibit no specialized anatomy, instead making use of body parts primarily used for other purposes. This is possibly due to the sporadic nature of nest building, minimizing the selective pressures of anatomy used for nest building. In general, birds are the most skilled nest builders, although not all species of birds build nests, some laying their eggs directly onto rock ledges or bare soil without first modifying
1775-399: Is usually motile whereas the female gamete cell, the ovum , is generally larger and sessile . The male and female gametes combine to produce the zygote cell. In multicellular organisms, the zygote subsequently divides in an organised manner into smaller more specialised cells, so that this new individual develops into an embryo . In most animals, the embryo is the sessile initial stage of
1846-656: The Maiasaura . Juvenile teeth at the site exhibit signs of wear, while the leg bones are not developed enough to walk. This allowed scientists to conclude that the species provided extensive parental care for its young. It is likely the species covered its nests with sand and vegetation to keep them warm and nested in colonies for increased protection. Social insects , including most species of ants , bees , termites , and wasps , are nest builders. Their often elaborate nests may be found above or below ground. Features often include ventilation systems and separate chambers for
1917-415: The coelacanths can reach a size of 9 cm (3.5 in) in diameter, and the young go through full development while in the uterus , living on the copious yolk. Animals are commonly classified by their manner of reproduction, at the most general level distinguishing egg-laying (Latin. oviparous ) from live-bearing (Latin. viviparous ). These classifications are divided into more detail according to
1988-528: The echidna lay eggs in nests. Gorillas build fresh nests daily out of leaves and other vegetation in which they sleep at night. They sometimes also build nests during the day for resting in. The smaller species of gorilla build their nests in trees, while the larger are confined to the ground. Nests of the western gorilla , the largest species, measure about 1 metre (3.3 ft) in diameter. Some species of frog build nests ranging from simple to modest complexity. Many stream-dwelling frogs lay their eggs in
2059-594: The planula , and either develops directly into the adult animals or forms new adult individuals through a process of budding . Microlecithal eggs require minimal yolk mass. Such eggs are found in flatworms , roundworms , annelids , bivalves , echinoderms , the lancelet and in most marine arthropods . In anatomically simple animals, such as cnidarians and flatworms, the fetal development can be quite short, and even microlecithal eggs can undergo direct development. These small eggs can be produced in large numbers. In animals with high egg mortality, microlecithal eggs are
2130-411: The salamanders . Eggs with a large yolk are called macrolecithal. The eggs are usually few in number, and the embryos have enough food to go through full fetal development in most groups. Macrolecithal eggs are only found in selected representatives of two groups: Cephalopods and vertebrates . Macrolecithal eggs go through a different type of development than other eggs. Due to the large size of
2201-413: The adult body, and by the yolk which the egg provides to nourish the embryo. Vertebrate eggs can be classified by the relative amount of yolk . Simple eggs with little yolk are called microlecithal , medium-sized eggs with some yolk are called mesolecithal , and large eggs with a large concentrated yolk are called macrolecithal . This classification of eggs is based on the eggs of chordates , though
Nest - Misplaced Pages Continue
2272-509: The air. The largest nests, built by members of genus Amitermes , stand nearly 7 metres (23 ft) tall with a similar circumference at the base, and host millions of individuals. Termite mounds are constructed to allow for excellent air flow, regulating the mound temperature. The mounds protect against drying and predation allowing many species to lose ancestral traits such as hard bodies, skin pigmentation, and good eyesight. Magnetic termites construct their nests with flattened sides along
2343-540: The air. Often the sex of the developing embryo is determined by the temperature of the surroundings, with cooler temperatures favouring males. Not all reptiles lay eggs; some are viviparous ("live birth"). Dinosaurs laid eggs, some of which have been preserved as petrified fossils. Among mammals, early extinct species laid eggs, as do platypuses and echidnas (spiny anteaters). Platypuses and two genera of echidna are Australian monotremes . Marsupial and placental mammals do not lay eggs, but their unborn young do have
2414-483: The ant is aware of its depth. It is hypothesized that they accomplish this by sensing the level of carbon dioxide in the soil. The leaf cutter ant builds a complex nest which can house 8 million individuals. Its nests feature numerous chambers, most notably garden chambers where they farm fungus on leaves they harvest from the forest. Species such as the carpenter ant and the wasp Polistes exclamans build "satellite nests" - smaller nests near, but separate from,
2485-407: The area. Complex nest building is considered to be one of the key adaptive advantages of birds. Nests help regulate temperature and reduce predation risks, thus increasing the chance that offspring live to adulthood. Bird nests vary from simple depressions in the ground known as scrapes to largely unstructured collections of branches to elaborately woven pendants or spheres. The megapodes , one of
2556-407: The basic principle extends to the whole animal kingdom . Small eggs with little yolk are called microlecithal. The yolk is evenly distributed, so the cleavage of the egg cell cuts through and divides the egg into cells of fairly similar sizes. In sponges and cnidarians , the dividing eggs develop directly into a simple larva, rather like a morula with cilia . In cnidarians, this stage is called
2627-492: The biological sense. In placental mammals , the egg itself is void of yolk, but develops an umbilical cord from structures that in reptiles would form the yolk sac. Receiving nutrients from the mother, the fetus completes the development while inside the uterus. Eggs are common among invertebrates , including insects , spiders , mollusks , and crustaceans . All sexually reproducing life, including both plants and animals, produces gametes . The male gamete cell, sperm ,
2698-404: The cells of incipient multicellular organisms. The cycle of the egg's formation is started by the gamete ovum being released ( ovulated ) and egg formation being started. The finished egg is then ovipositioned and eventual egg incubation can start. Scientists often classify animal reproduction according to the degree of development that occurs before the new individuals are expelled from
2769-401: The complex tissues that identify amniotes. The eggs of the egg-laying mammals (the platypus and the echidnas ) are macrolecithal eggs very much like those of reptiles . The eggs of marsupials are likewise macrolecithal, but rather small, and develop inside the body of the female, but do not form a placenta . The young are born at a very early stage, and can be classified as a " larva " in
2840-476: The crowded cliff ledges on which they breed. Yolks of birds' eggs are yellow from carotenoids , it is affected by their living conditions and diet. Bird eggshells are diverse. For example: Tiny pores in bird eggshells allow the embryo to breathe. The domestic hen 's egg has around 7000 pores. Some bird eggshells have a coating of vaterite spherules , which is a rare polymorph of calcium carbonate. In Greater Ani Crotophaga major this vaterite coating
2911-438: The disadvantage of weakening wood in manmade structures. The abundance of biological resources within the nest has led to a number of specialized predators. The aardvark and the ant eater use long tongues to prey upon termite and ant nests. Birds such as the honey buzzard specialize on wasp and bee nests, a resource also targeted by the tropical hornet . Symbiosis , ranging from feeding on waste to obligate parasitism ,
Nest - Misplaced Pages Continue
2982-436: The few groups who do not directly brood their young, incubate their young in a mound of decomposing vegetation. One species, Macrocephalon maleo , uses volcanic sand warmed by geothermal heat to keep its eggs warm. Among the simple nest builders are falcons , owls , and many shorebirds . The weavers exhibit perhaps the most elaborate nests, complete with strands of grass tied into knots. Most bird nests lie somewhere in
3053-650: The genera Dasypeltis and Elachistodon specialize in eating eggs. Brood parasitism occurs in birds when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include the cowbirds and many Old World cuckoos . Like amphibians, amniotes are air-breathing vertebrates , but they have complex eggs or embryos , including an amniotic membrane . Amniotes include reptiles (including dinosaurs and their descendants, birds) and mammals. Reptile eggs are often rubbery and are always initially white. They are able to survive in
3124-424: The ground to protect themselves and their young. Prairie dogs build an elaborate system of tunnels which can span large stretches of land. One such structure, called a town, spanned 25,000 square miles (65,000 km) and held an estimated 400 million individuals. Their homes are adapted to withstand large (above-ground) temperature variation, floods, and fire. Their young are raised in the deepest chambers where
3195-481: The ground, creating, each cell made from circular disks cut from plant leaves using the bee's mandibles. Bee nests are founded upon the wax the secrete from their bodies, while those of wasps are dependent on their ability to turn plant water into paper using their saliva. Nests often exhibit divided living, with eggs and food stores kept in distinct parts of the hive. Vespid wasps build complex nests from paper-like material where they lay eggs in individual cells. When
3266-494: The individual life cycle, and is followed by the emergence (that is, the hatching) of a motile stage. The zygote or the ovum itself or the sessile organic vessel containing the developing embryo may be called the egg. A recent proposal suggests that the phylotypic animal body plans originated in cell aggregates before the existence of an egg stage of development . Eggs, in this view, were later evolutionary innovations , selected for their role in ensuring genetic uniformity among
3337-411: The larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a critical point after which they must learn how to hunt and feed or they will die. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized and develop internally. However, the larvae still grow inside the egg consuming the egg's yolk and without any direct nourishment from
3408-465: The main nest. These satellite nests are used as an insurance against predators and parasites ; if the original nest is attacked, surviving members can move the satellite nest. Other species such as the Black hover wasp, Parischnogaster alternata , construct nests in clusters with the central core composed of older colonies surrounded by younger colonies. The Eastern carpenter bee, Xylocopa virginica ,
3479-413: The middle, with the majority building cup-shaped nests using some combination of mud, twigs and leaves, and feathers. Some birds, such flamingos and swifts , use saliva to help hold their nest together. The edible-nest swiftlet uses saliva alone to construct their nests. The rufous hornero nest is composed entirely of mud and feces, which is placed on tree branches to allow the sun to harden it into
3550-528: The most basic level, there are only two types of nest building: sculpting and assembly. Sculpting is the process of removing material to achieve the desired outcome. Most commonly this entails burrowing into the ground or plant matter to create a nesting site. Assembly entails gathering, transporting, and arranging materials to create a novel structure. Transportation has the greatest time and energy cost so animals are usually adapted to build with materials available in their immediate environment. Plant matter
3621-418: The mother also providing direct nourishment. The eggs of fish and amphibians are jellylike. Cartilaginous fish (sharks, skates, rays, chimaeras) eggs are fertilized internally and exhibit a wide variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them. These eggs do not have
SECTION 50
#17327798279733692-432: The mother. The mother then gives birth to relatively mature young. In certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mother's body. This is known as intrauterine cannibalism . In certain scenarios, some fish such as the hammerhead shark and reef shark are viviparous , with the egg being fertilized and developed internally, but with
3763-660: The nest's style. Several species will build on a cactus whenever possible. The bushtit and Bullock's oriole will suspend their nests from the tips of slender branches. The oropendolas take hanging nests to the extreme, constructing pouches up to 1.8 metres (5.9 ft) tall using hanging vines as their base. The hanging nest is attached to thin tree branches, discouraging predation. Other species seek out crevices, using buildings or birdhouses when tree holes are not available. Typical bird nests range from 2 centimetres (0.79 in) in size ( hummingbirds ) to 2 metres (6.6 ft) ( eagles ) in diameter. The largest nest on record
3834-421: The norm, as in bivalves and marine arthropods. However, the latter are more complex anatomically than e.g. flatworms, and the small microlecithal eggs do not allow full development. Instead, the eggs hatch into larvae , which may be markedly different from the adult animal. In placental mammals, where the embryo is nourished by the mother throughout the whole fetal period, the egg is reduced in size to essentially
3905-412: The north–south axis to ensure maximum warming during the winter, while exposing minimal surface area to the harshest mid-day sunshine. Other termite species use their nests to farm fungi. Ant nests feature an elaborate colony structure that may extend 2 metres (6.6 ft) or more underground. As the structure gets further underground, individual chambers become farther and farther apart indicating that
3976-537: The occurrence of physical features such as evidence of excavation. The Oviraptor nests of Mongolia are perhaps the most famous case of dinosaur nesting. One specimen was found fossilized atop a nest in a brooding posture, proving the animal had been poorly named (Oviraptor means "egg taker"). A site known as Egg Mountain in Montana provides exceptional evidence of dinosaur nesting behavior. The site features dozens of nests each with 20 or more eggs belonging to
4047-413: The pointed end develops at the back. . One hypothesis is that long, pointy eggs are an incidental consequence of having a streamlined body typical of birds with strong flying abilities; flight narrows the oviduct, which changes the type of egg a bird can lay. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait
4118-421: The queen, her eggs, and developing individuals. Bees and hornets often seek out natural cavities in which to construct their nests, also known as hives, in which they store food and raise their young. Other species of bee and some wasps dig holes in the ground or chew through wood. In the species Megachile rotundata , for example, females construct tubular-shaped nests in rotting wood as well as small holes in
4189-568: The small size of the eggs does not allow for direct development, and the eggs hatch to a larval stage ("fry"). In terrestrial animals with macrolecithal eggs, the large volume to surface ratio necessitates structures to aid in transport of oxygen and carbon dioxide, and for storage of waste products so that the embryo does not suffocate or get poisoned from its own waste while inside the egg, see amniote . In addition to bony fish and cephalopods, macrolecithal eggs are found in cartilaginous fish , reptiles , birds and monotreme mammals. The eggs of
4260-549: The smallest known bird egg, which measures between 6.35–11.4 millimetres (0.250–0.449 in) long and weighs half of a gram (around 0.02 oz). Some eggs laid by reptiles and most fish, amphibians, insects, and other invertebrates can be even smaller. Reproductive structures similar to the egg in other kingdoms are termed " spores ", or in spermatophytes " seeds ", or in gametophytes "egg cells". Several major groups of animals typically have readily distinguishable eggs. The most common reproductive strategy for fish
4331-405: The soft eggs to protect them from the sun and predators and leave. From the fossil record, it is known that many, or perhaps all, dinosaurs laid eggs. Paleontologists have identified a number of features that allow them to distinguish a nesting site from a random clustering of eggs. Those include regular clustering patterns, the co-occurrence of whole eggs with broken eggs and/or hatchlings, and
SECTION 60
#17327798279734402-416: The soil. For the same reason, later eggs in a clutch are more spotted than early ones as the female's store of calcium is depleted. The color of individual eggs is also genetically influenced, and appears to be inherited through the mother only, suggesting that the gene responsible for pigmentation is on the sex-determining W chromosome (female birds are WZ, males ZZ). It used to be thought that color
4473-471: The structure. Other birds often built their own nests on top of Weaver nest sites. Some birds build nests in trees , some (such as eagles , vultures , and many seabirds ) will build them on rocky ledges, and others nest on the ground or in burrows . Each species has a characteristic nest style, but few are particular about where they build their nests. Most species will choose whatever site in their environment best protects their nest, taking into account
4544-457: The temperature is the most stable. Many mammals, including raccoons and skunks , seek natural cavities in the ground or in trees to build their nests. Raccoons, and some rodents, use leaves to build nests underground and in trees. Tree squirrels build their nests ( dreys ) in trees, while voles nest in tall grass. In some species, the nest serve as homes for adults while in others they are used to raise young. The duck-billed platypus and
4615-640: The wasp Mischocyttarus mexicanus is known to nest in groups or alone depending on the distribution of potential nest sites in the area. Nest sizes vary dramatically and the largest wasp nest on record measured 1.75 metres (5.7 ft) in diameter and was 3.7 metres (12 ft) tall. Found in New Zealand, it was likely built by the German wasp . Termites build elaborate nests that span multiple generations and may last decades. Using chewed wood, mud, and feces they build large mounds which may extend well into
4686-432: The yolk, the cell division can not split up the yolk mass. The fetus instead develops as a plate-like structure on top of the yolk mass, and only envelopes it at a later stage. A portion of the yolk mass is still present as an external or semi-external yolk sac at hatching in many groups. This form of fetal development is common in bony fish , even though their eggs can be quite small. Despite their macrolecithal structure,
4757-449: The young hatch, their parents feed them chewed up larvae. Different species exhibit different nest structures. Paper wasp nesting consist of a single tier of cells, while yellow jacket nests can be many layers thick, reaching up to 30 centimetres (0.98 ft) in diameter. Nesting strategies can be plastic, for instance the wasp Parischnogaster mellyi will significant vary its nest construction based on environmental conditions, and
4828-457: The young to the water where she continues to care for them for another year. Alligators are very particular about their nesting sites and will abandon a site if things go wrong. Cobras use leaves and other debris to build nests in which they lay eggs that both sexes guard. They carry the vegetation to the nest site by kinking their necks. Sea turtles dig a hole in the sand above the high tide line in which they lay their eggs. They then cover
4899-442: Was 30 cm × 14 cm × 9 cm (11.8 in × 5.5 in × 3.5 in) in size. Whale shark eggs typically hatch within the mother. At 1.5 kg (3.3 lb) and up to 17.8 cm × 14 cm (7.0 in × 5.5 in), the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some non-avian dinosaurs laid larger eggs. The bee hummingbird produces
4970-456: Was applied to the shell immediately before laying, but subsequent research shows that coloration is an integral part of the development of the shell, with the same protein responsible for depositing calcium carbonate, or protoporphyrins when there is a lack of that mineral. In species such as the common guillemot , which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own eggs on
5041-678: Was made by a pair of bald eagles . It was 2.9 metres (9.5 ft) in diameter, 6 metres (20 ft) deep and was estimated to weigh more than 2 tonnes (4,400 lb). The lightest bird nests may weigh only a few grams. Incubation mounds of the mallee fowl can reach heights of 4.57 metres (15.0 ft) and widths of 10.6 metres (35 ft). It is estimated the animal uses as much as 300 tonnes (660,000 lb) of material in its construction. The extinct Sylviornis neocaledoniae may have constructed nesting mounds 50 metres (160 ft) in diameter. Many species of small mammals such as rodents , rabbits , and ground squirrels dig burrows into
#972027